The research program outlined herein continues our work already in progress on the synthesis of the tetracyclic diterpene aphidicolin, a potent antiviral agent that is active against a range of DNA-containing viruses including Herpes simplex. The present synthetic approach is based on our previous research on the acid-catalyzed and photochemical isomerizations of propellanes. We also propose here to employ similar methods in a synthesis of stemodinol, a diterpene similar to aphidicolin that is isolated from a plant used in the Caribbean islands for treatments of venereal disease. In addition to the synthesis of these diterpenes we plan to initiate a novel stereospecific synthesis of the commercially important member of the tricyclovetivene family khusimone.